JP6731082B2 - Seat belt pretension retractor assembly - Google Patents

Description

TECHNICAL FIELD The technical field relates generally to seatbelt restraint systems for restraining vehicle occupants, and more particularly to devices for pretensioning seatbelts.

Seat belt restraint systems for restraining an occupant in a vehicle seat play an important role in reducing occupant injury in a vehicle crash situation. Conventional so-called "three-point" seat belt restraint systems have in common a lap belt section that extends over the pelvis of the occupant and a shoulder belt section that intersects the upper torso, which are fastened together. Alternatively, it is formed by a continuous length of seat belt webbing. The lap and shoulder belt sections are connected to the vehicle structure by anchorages. Belt retractors are typically provided to house the belt webbing and may further act to manage belt tension loading in crash situations. Seat belt restraint systems (so-called "active" types) that are manually deployed by the occupant also typically include a buckle attached to the vehicle body structure by an anchorage. A latch plate attached to the belt webbing is received by the buckle and allows the belt system to be fastened to allow restraint and removed to allow entry and exit from the vehicle. To do. The seat belt system, when deployed, effectively restrains the occupant during a crash.

OEM vehicle manufacturers include seatbelts with pretensioning devices that pull the seatbelt (also known as "front pretensioners") during or even before the impact of the vehicle to improve occupant restraint performance. Often provide restraint systems. The pretensioner removes slack in the webbing and allows the belt restraint system to engage the occupant early in the crash sequence. One type of pretensioner acts on the webbing retractor to pull the belt. Various designs of retractor pretensioners include the type currently known and known as rotopretensioners, which incorporates a gas generator for producing pyrotechnic charges. Examples of such rotopretensioners include U.S. Pat. No. 5,881,962, filed April 11, 1995, U.S. Patent Application Publication No. 2006/0243843, filed April 27,2005, No. 2012/0006925, filed July 6, 2010, and US Patent No. 7,988,084, filed August 2, 2011, by assignee of the present application. Shared and, for all purposes, incorporated herein by reference in their entirety. In general, ignition of pyrotechnic charge or other combustible material creates a gas pressure in a chamber with a piston to move a driving element, such as a piston, rack and pinion, or series of spheres, located within a pretensioner tube. Which engages the retractor spool sprocket and winds it to retract the webbing.

One problem with pretensioners that use a series of metal spheres is the weight of the series of spheres required for a full pretension stroke, as well as the corresponding cost of supplying multiple metal spheres with tight tolerances. .. Further, for pretensioners that use a series of metal spheres, or rack and pinion based systems, there is a need for synchronization or clutch features that ensure that the series of spheres or pinions are fully engaged with the retractor spool sprocket.

Another problem with pretensioners is known as the low resistance state, which means that the drive element reaches the end of the stroke without experiencing substantial resistance. This can occur if there is excessive slack in the seat belt webbing. In these cases, the low resistance results in a lower amount of back pressure from the drive element. Since back pressure is generated by the engagement between the drive element and the sprocket, lower back pressure reduces the pressure on the sealing element leading to the drive element. The reduced pressure on the sealing element reduces the amount by which the sealing element is circumferentially compressed. The reduced sealability may result in gas leaking out of the tube around the series of spheres.

A further problem with pretensioners is the need to keep the retractor and seat belt webbing locked at the end of the pretension stroke. When the retractor spool is not left locked, payback can occur, causing the seat belt not to be rolled up and reintroducing slack in the seat belt. One way to maintain the locked position involves maintaining the pressure from the gas generator beyond the amount required for the pretension stroke. However, this adds weight and cost.

Another type of pretensioner replaces a metal sphere as the driving element. Instead of metal spheres, flexible rods may be used as drive elements. The flexible rod is made of a polymer and may have an elongated shape. Polymer rods of different cross-sectional shapes may be used. The polymer rods are driven in a manner similar to metal spheres, with the gas generator producing charge at one end and increasing pressure to drive the rods through the channel and engage the sprockets or pinions. The pinion is operably connected to the spindle such that when the rod engages the pinion and rotates the pinion, the pinion causes the spindle to rotate and wind the seat belt web ring.

Known pretensioner assemblies include a plurality of components that are assembled together to rotate a pinion in response to actuation by a drive element and further rotate a spindle accordingly. For example, the assembly may include a tread head, a two-piece pinion, a bearing disc, bending elements, a torsion bar, and a spindle. The two-piece spindle and bending element are mounted on the tread head, and the bearing disc is mounted on one side of the spindle. The torsion bar is mounted on the tread head at one end and on the spindle at the opposite end. These assemblies can include problems with accumulating axial tolerances as well as assembly time. Furthermore, the need to transfer torque between the assembled components necessitates a fixed mounting interface against rotation, thus providing a jagged or peripheral surface including protrusions.

Seatbelt pretension retractor assemblies for use in passenger vehicles are provided herein. In an exemplary embodiment, the pre-tensioning device for use in the seat belt retractor assembly is a rotatable spindle configured to wind up seat belt webbing in response to rotation of the spindle, the spindle comprising: A spindle and a treadhead pinion operably coupled to the spindle that rotates about a longitudinal axis, the treadhead pinion configured to rotate in response to an applied pre-tension load. And tread head rotation, which rotates the spindle, translates along a predetermined path in response to actuation of the tread head pinion and rod, and is deformable configured to directly engage the tread head pinion. A rod that rotates the tread head pinion by translation of the rod and engagement with the tread head pinion.

The tread head pinion may be integrally formed and extend between a first side facing away from the spindle and a second side facing the spindle and between the first side and the second side. A ring portion having a plurality of radially projecting teeth for receiving a pretensioning load from the rod, a first flange on a first side, disposed on both sides of the teeth, and a second flange on a second side. A pair of flanges projecting radially outward beyond the teeth, the flanges being longitudinally disposed adjacent to the plurality of teeth, the teeth being integral with the flange. A flange and a bearing portion axially projecting from the second flange toward the spindle, the bearing surface defining a cavity between the adjacent tooth and the flange, the bearing surface contacting the spindle. And a bearing portion that defines

In another embodiment, a pretensioning device for use in a seat belt retractor assembly is a rotatable spindle configured to wind seat belt webbing in response to rotation of the spindle, the spindle having a central longitudinal length. A spindle, rotating about a directional axis, and a treadhead pinion operably coupled to the spindle, the treadhead pinion configured to rotate in response to application of a pre-tension load, The rotation of the tread head causes the spindle to rotate, the tread head pinion and the deformable rod configured to translate along a predetermined path in response to actuation of the rod and directly engage the tread head pinion. A rod that rotates the tread head pinion by translation of the rod and engagement with the tread head pinion.

The tread head pinion may be integrally formed and extend between a first side facing away from the spindle and a second side facing the spindle and between the first side and the second side. And a ring portion having a plurality of radially projecting teeth for receiving a pretensioning load from the rod, a first flange on the first side arranged on both sides of the teeth and a second flange on the second side. A second flange extending radially outward beyond the teeth, the flanges being longitudinally disposed adjacent the plurality of teeth, the teeth being integral with the flange. And a flange defining a cavity between the adjacent teeth and the flange. The torsion bar may extend into the internal cavity defined by the ring portion of the treadhead pinion and may be attached to the treadhead pinion at the first end and the spindle at the second end.

Further objects, features and advantages of the present invention will become apparent to those skilled in the art to which the present invention pertains by considering the following description and appended claims in conjunction with the accompanying drawings. Ah

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

FIG. 6 is a perspective view of an occupant restraint system, according to an example embodiment.

FIG. 6 is a perspective view of an occupant restraint system with various components removed to show a seat belt pretension retractor assembly according to an exemplary embodiment.

FIG. 6 is a perspective view of a seat belt pretension retractor assembly, according to an example embodiment.

FIG. 5 is a cross-sectional view of a seat belt pretension retractor assembly illustrating a tube, a plastically deformable polymer rod, and a tread head pinion in a non-actuated position, according to an example embodiment.

FIG. 6 is an exploded view illustrating a pretension assembly including a tread head pinion, a flex element, a flex element insert, a torsion bar, and a spindle.

6 illustrates a flexing element crimped to a tread head pinion.

It is a perspective view of a tread head pinion.

It is sectional drawing of a tread head pinion.

It is a cross-sectional perspective view of a tread head pinion.

It is a perspective sectional view of a tread head pinion.

FIG. 6 is a cross-sectional view of a tread head pinion and a deformable polymer rod.

1 illustrates a multi-piece assembly of prior art pretensioner components.

6 illustrates another treadhead pinion.

FIG. 6 is a side cross-sectional view of a plastically deformable polymer rod and stopper, according to an exemplary embodiment.

FIG. 6 is a side cross-sectional view of a plastically deformable polymer rod and stopper according to another exemplary embodiment.

FIG. 6 is a cross-sectional view of a gas generator, seal, stopper, and plastically deformable polymer rod of a seat belt pretension retractor assembly in a non-actuated position, according to an exemplary embodiment.

FIG. 6 is a cross-sectional view of a seat belt pretension retractor assembly in an actuated position according to an exemplary embodiment.

FIG. 6 is a partially exploded perspective view of a tube, a plastically deformable polymer rod, and a stopper, according to an exemplary embodiment.

It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

The following description is merely exemplary in nature and is not intended to limit the present disclosure or its application or uses.

Referring now to the drawings, FIG. 1 illustrates a vehicle seat 10 and seatbelt assembly 12 according to an exemplary embodiment. The seat belt assembly 12 includes a seat belt webbing 14 having a shoulder belt portion 16 extending from an upper guide loop or anchorage 18 to a latch plate 20 and a lap belt portion 22 extending from the latch plate 20 to an anchorage 24. The latch plate 20 can include a loop portion 26 through which the seat belt webbing 14 extends. The latch plate 20 can be inserted into the seat belt buckle 28 to lock and unlock the seat belt assembly 12. The seat belt buckle cable 30 secures the seat belt buckle 28 to a portion 31 of the vehicle structure (eg, vehicle frame), either directly or in cooperation with other components. It is understood that other manners of attaching the seat belt webbing 14 to the vehicle may be used, including modifications to the latch plate 20 and the seat belt buckle 28, and their attachment to the seat belt webbing 14 and its associated vehicle structure. Will

The seat belt webbing 14 is positioned within the vehicle seat 10 (in an integrated structural seat design) or structurally coupled to the vehicle body of a seat belt pretension retractor assembly or retractor assembly 32 (FIGS. 2 and 3). (Shown in FIG. 3), so that the effective length of the seat belt webbing 14 can be adjusted. When the latch plate 20 is fastened to the seat belt buckle 28, the seat belt assembly 12 defines a three point constraint between the anchorage 18, the latch plate 20, and the anchorage 24. Any other suitable configuration may be used in the present invention, such as alternative locations for retractor assembly 32, latch plate 20, and anchorage 24.

Referring now to FIG. 2, an isometric view of seatbelt assembly 12 is illustrated without association with a vehicle and illustrates retractor assembly 32 in accordance with an exemplary embodiment. The retractor assembly 32 includes a spool assembly 34 and a gas generator 36 mounted on a common frame 38. The spool assembly 34 is connected to and receives the seat belt webbing 14 of the shoulder belt portion 16 so that the end of the lap belt portion 22 of the seat belt webbing 14 is at an anchorage point, such as the frame 38. , Or seat 10 (shown in FIG. 1), or another part of the vehicle, such as a floor pan, fixedly engaged.

Still referring to FIG. 3, the spool assembly 34 includes a belt spool or spindle 40 that engages the shoulder belt portion 16 of the seat belt webbing 14 and rotates to wind or unwind the seat belt webbing 14. A torsion “clock” or “motor” type spring is carried within the spring end cap 42 and rotatably biases the belt spool 40 to retract the seat belt webbing 14. Spool assembly 34 includes other pre-tensioners, inertial and webbing sensitive locking devices, torsion bar load limiters, or other belt control devices known in accordance with the prior art, some of which are described in further detail below. A spool control mechanism may be further incorporated. A "spool control system" as referred to herein may include any system that controls the rotational movement of a webbing spool and thus the withdrawal and retraction of a seat belt webbing. One of such spool control systems is an electric assist retractor. The spool locking device typically incorporates an inertial sensing element such as a rotating sphere or pendulum to provide that the sprockets of the spool are engaged and prevent further withdrawal of the seat belt webbing 14 from the belt spool 40. The webbing sensing locking device senses the rapid unwinding of the seat belt webbing 14 to lock the retractor assembly 32. Various electronic sensing mechanisms that detect the withdrawal of the seat belt webbing 14 and/or the connection of the latch plate 20 to the seat belt buckle 28 may also be incorporated within the retractor assembly 32.

During normal vehicle operation, the retractor assembly 32 allows unwinding of the seat belt webbing 14 to provide the occupant a certain amount of freedom of movement. However, if an impact or potential impact situation is detected, the retractor assembly 32 is locked to prevent unrolling and secure the occupant within the seat 10. For example, the retractor assembly 32 is locked when the vehicle slows down at a predetermined rate, or when the brake operates with a predetermined force. Due in part to the free unwinding of the seat belt webbing 14, the seat belt assembly 12 often experiences slack during normal use.

FIG. 4 provides an illustration of a cross section of the pretensioner system 44, according to an exemplary embodiment. 3-4, in particular, the retractor assembly 32 further incorporates a pretensioner system 44 that is operably connected to the spool assembly 34 and that is operable to rotate the belt spool 40 for pretensioning. As is known to those skilled in the art, retractor pretensioners wind the seat belt webbing into the more taught condition for the occupant during the early stages of the detected vehicle impact. This is provided to reduce forward movement or deviation of the occupant in response to the vehicle's impact or deceleration force due to rollover.

The pretensioner system 44 includes a pretensioner tube 52 that communicates with the gas generator 36. The gas generator 36 is used to provide inflation gas in response to the firing signal. As known in the art, for example, vehicles include a sensor array that signals an emergency event such as an impact event, a crash, or a rollover. The vehicle sensor may be a specific impact sensor, or may be a conventional vehicle sensor (eg, a longitudinal or lateral acceleration sensor), or otherwise part of a control system having a set of multiple sensors. Good. Any other shock sensor known to or will be known to one of ordinary skill in the art can also be readily used in conjunction with the seat belt assembly 12 of the present invention. An electronic control unit, such as a central processing unit (CPU) or other controller, receives the signal and causes the seatbelt assembly 12 to actuate the vehicle seatbelt webbing 14 (eg, via pretensioner activation). Control to respond by tightening.

As discussed in more detail below, the pretensioner tube 52 may be, for example, an elongated shape, such as a plastically deformable polymer rod disposed therein that is flexible within the tube 52. , A pretensioner rod 53. As will be discussed more specifically and in more detail below, the pretensioner rod 53 has a generally straight shape when disposed on the outside of the pretensioner tube 52 prior to insertion therein, When inserted into the tube 52, it will bend and flex according to the serpentine shape of the tube 52.

In normal use, the spool assembly 34 will rotate relative to the common frame 38 to wind the seat belt webbing 14 attached to the spool assembly 34. The common frame 38 includes a housing 54 for housing the components of the pretensioner system 44.

5A and 5B, the pretensioner system 44 includes a pretensioner assembly 60 that may include a spool or spindle 40, a torsion bar 62, a treadhead pinion 64, and a flexing element 66. As described in more detail below, the treadhead pinion 64 may include a number of features heretofore included in separate assembly parts. FIG. 5A illustrates an exploded view in which the tread head pinion 64 is arranged to be directly attached to the torsion bar 62 (which is inserted into the tread head pinion 64), which also includes the spindle 40 (of the spindle). It is arranged to be directly attached to the inside (not shown). Bending element 66, which may be a progressive bending element, attaches to both treadhead pinion 64 and spindle 40. Bending element 66 may be attached to spindle 40 via bending element insert 67. Once assembled, the spindle 40 abuts the tread head pinion 64, allowing the spindle 40 to rotate relative to the tread head pinion 64 during pre-tension, if desired. FIG. 5B illustrates bending element 66 attached to tread head pinion 64.

The torsion bar 62 and bending element 66 operate in a manner well known in the art, which allows adjustment of the load applied to the occupant during pretensioning. For example, the torsion bar 62 may rotate in response to loads above a predetermined level on the seat belt and spindle. Therefore, allowing the torsion bar 62 and the spindle to rotate with respect to the pretensioned and locked tread head pinion 64 allows for some unwinding of the seat belt web ring. The unrolling that occurs reduces the load on the passenger for a completely locked belt.

5A to 6, the tread head pinion 64 is integrally formed. The pinion 64 may be formed by sintering or die casting and may be made of zinc or aluminum. The tread head pinion 64 may be described herein with reference to various parts and features of a one-piece design. It will be appreciated that reference to various portions or features is intended to refer to integrally designed portions or features of the tread head pinion 64.

The tread head pinion 64 has a generally circular shape so that the tread head pinion 64 can rotate generally along the spindle (although during high load, the relative rotation between the tread head pinion 64 and the spindle is This is possible depending on the deformation of the bar 62). The tread head pinion 64 is also described as having a disc-like shape, with the first side 70 facing a first direction and the second side 72 facing a second direction opposite the first direction. You can The pinion 64 may also include a body portion 74 that extends axially between the first side and the second side. The tread head pinion 64 has a central axis A about which the tread head pinion 64 rotates with the spindle.

The first side 70 is located axially further from the spindle 40 than the second side 72. In other words, the first side 70 faces away from the spindle 40 and the second side 72 faces the spindle 40. The second side 72 is arranged to engage the spindle 40 during assembly.

The first side 70 may include a variety of structures that accommodate the conventional functionality of seat belt spool assemblies, such as structures that cooperate with inertial locks. The first side 70 may include a shaft portion 76 that projects axially outwardly from the first side 70. The shaft portion 76 cooperates with the frame or assembly housing or other structure to allow the tread head pinion 64 to rotate during unwinding or winding of the web under normal operating conditions, depending on pretension. The tread head pinion 64 rotates and is arranged so that the seat belt webbing can be wound up.

The body 74 of the tread head pinion 64 is arranged to receive the drive element of the pretension assembly. The drive element may be in the form of a polymeric rod 53 that is driven through the tube 52 and engages the radially outer portion of the tread head pinion 64. When the polymer rod 53 engages the radially outer portion of the pinion 64, the pinion 64 will rotate in response to the driving force of the polymer rod 53. Although the use of the polymeric rod 53 as a drive element is described herein, it will be appreciated that the integral tread head 64 aspect may also be used with other types of drive elements.

With reference to FIGS. 6 and 7A-7C, the body 74 receives a ring portion 78 that extends circumferentially around a radially outer edge of the body 74 and defines a radially outer surface of the tread head pinion 64. Including a drive element to operate. The ring portion 78 includes a first flange 78a and a second flange 78b. The first flange 78a is located adjacent the first side 70 and the second flange 78b is located adjacent the second side 72.

The flanges 78a and 78b extend radially outward from the central axis A and define an internal space 78c axially between the first flange 78a and the second flange 78b. The space 78c between the flanges 78a, 78b is designed to receive a polymer rod 53 or other drive element that is driven during pretension to engage the tread head pinion 64.

Thus, the flanges 78a and 78b have an inner surface and an outer surface, the inner surface facing the interior space 78c and the outer surface facing axially outward.

The flanges 78a and 78b may include chamfered inner edges 78d at radially outer inner corners of the flanges 78a and 78b. This chamfered edge 78d may operate to guide the drive element or polymer rod 53 into the interior space 78c during pretensioning. Therefore, the chamfered edge 78d preferably extends circumferentially around the entire perimeter of the flanges 78a and 78b. One or both of the flanges 78a and 78b may include a radially outward notch 78e extending into the flanges 78a and 78b.

Ring 78 further includes a plurality of teeth 80 extending between flanges 78a and 78b in interior space 78c. The teeth 80 engage the drive element 53 so that when the drive element 53 is driven during pre-tension, the drive element affects the tooth 80 to rotate the tread head pinion 64 and the attached spindle 40. Designed to do. The teeth 80 are preferably evenly circumferentially spaced around the ring 78.

In one form, and with further reference to FIG. 8, when looking at a cross-sectional view of the tooth 80 in the axial direction, the tooth 80 has a radially outward apex 80a, a first surface 80b, and a second surface 80c. Have respectively. The first surface 80b and the second surface 80c may be arranged at different angles with respect to the apex and the central axis A.

For example, in one approach, the first surface 80b is angled from the reference line α so that α is less than or equal to β, with reference to the line L extending from the axis A passing through one vertex 80a of the tooth 80. And the second surface 80c is positioned at an angle β from the reference line. In a preferred embodiment, the angle α is smaller than the angle β. In one example, the angle α can be approximately 25 degrees and the angle β can be approximately 30 degrees.

The first surface 80b is preferably the side of the tooth 80 facing the drive element 53 so that when the drive element 53 is driven into engagement with the tooth 80, the drive element affects the first surface 80b. Is located in. Due to the small angle of the first surface 80b, the ratio of tangential force to radial force of the pinion increases when the drive element 53 begins to press against the tread head pinion 64.

Ring 78 may also include a basal surface 82 located radially inward from apex 80a of tooth 80. The base surface 82 may define the base of the tooth 80. The intersections of teeth 80, flanges 78a and 78b, and base surface 82 may be in the form of fillets 82a, thus defining a plurality of curved pockets 84 within interior space 78c. The fillet 82a thus occupies a portion of the interior space 78c and reduces the ability of the polymer rod to deform into a space near the intersection of the teeth 80, flanges 78a/b, and base surface 82. Excessive rod deformation wastes energy. Therefore, reducing the deformable space of the rod 53 may reduce the amount of potential wasted energy.

Referring again to FIGS. 6, 7A, and 7B, the second side 72 of the treadhead pinion 64 includes structure that attaches to the torsion bar 62 and flexing element 66 and provides the spindle 40 with a bearing surface. The second side 72 includes a spindle bearing portion 84 that extends axially outwardly away from the second flange 78b. The bearing portion 84 has a substantially circular shape and forms a step surface extending from the main body 74 and the second flange 78b. The bearing portion 84 has an outer diameter smaller than the outer diameter of the second flange 78b so that the second flange 78b extends radially outward with respect to the bearing portion 84.

The bending element mounting portion 86 extends axially outward from the bearing portion 84. The bending element mounting portion 86 has a generally circular shape with an outer diameter smaller than the outer diameter of the bearing portion 84 such that the bearing portion 84 extends radially outward from the bending element mounting portion 86.

The flex element mounting portion 86, bearing portion 84, and body 74 of the integrated tread head pinion 64 combine to extend axially outwardly from the axially outer surface of the bearing element mounting portion 86 into the tread head pinion 64. Defining an internal cavity 88 in which The cavity 88 is at the center of the axis A and has a spline shape when viewed in the axial direction. The spline shape of the cavity 88 corresponds to the end shape of the torsion bar 62 so that the torsion bar 62 is axially inserted into the cavity 88 and rotatably fixed to the tread head pinion 64. The spline shape of the cavity 88 and the torsion bar 62 operate to transfer torque between the tread head pinion 64 and the torsion bar 62.

The bending element mounting portion 86 includes a notch 86a extending radially inward from the outer peripheral surface of the bending element mounting portion 86. Notches 86a provide pockets or spaces in which the ends of bending element 66 can be placed.

Bearing portion 84 also includes a crimp pocket 84a axially disposed adjacent notch 86a such that the space of notch 86a communicates with pocket 84a. The pocket 84a extends axially inward into the bearing portion 84.

Therefore, the ends of the bending element 66 may be axially inserted into the notches 86a and pockets 84a. The bearing portion 84 also includes an access cavity 84b that extends axially inward into the bearing element at a location disposed radially adjacent to the swage pocket 84a and outwardly therefrom. Therefore, the crimp wall 84c is defined between the pocket 84a and the cavity 84b. The crimp wall 84c is radially deformable and crimps the end of the flexing element 66 (inserted into the pocket 84a) against the end of the tread head pinion 64.

The bending element mounting portion 86 has a continuously smooth outer peripheral surface over most of the outer circumference. Therefore, the outer peripheral surface has a substantially constant diameter over most of the outer periphery, except for the area where the notch 86a is located.

Referring to FIG. 9A, prior art tread heads required the splined outer surface of tread head 464 (bending element 66 would wrap around it). This was because the tread head 464 and pinion 478 were separate. The pinion 478 has a spline inner opening that cooperates with the spline outer surface of the tread head 464 such that the tread head 464 can be assembled to the pinion 478 and the torque from the pinion 478 is transmitted to the tread head 464. Inclusive. The spline portion of the tread head 464 extended through the pinion 478 and protruded outwardly, and the portion protruding beyond the pinion 478 was the portion encased by the flexion element 66. This portion of the tread head 464 needs to be splined as the spline pinion 478 needs to pass through during assembly.

As shown in FIG. 6, the bending element 66 is provided with a smooth bearing outer peripheral surface 86 b around the bending element mounting portion 86 instead of the spline bearing surface.

Further, as explained above, the bearing portion 84 extends axially outward from the flange 78b. The bearing portion 84 provides a bearing surface 84d with which the spindle 40 can abut when the spindle 40 rotates relative to the pinion 64. During normal operation of the retractor, the spindle 40 does not rotate with respect to the tread head 64. However, when the torsion bar 62 rotates according to the load on the seat belt web ring, the spindle 40 rotates with respect to the tread head 64 and abuts on the bearing portion 84.

The bearing surface 84d has a generally annular shape that surrounds the flex element mounting portion 86. The cavity 84a described above for crimping the bending element 66 extends axially into the bearing surface 84d. In addition to the cavity 84a, the bearing portion 84 may further include a plurality of core outs 84e. Core out 84e is in the form of a cavity or other hole formed in bearing surface 84d. The core outs 84e reduce the overall weight of the tread head 64 and the integral form of the tread head 64 allows the bearing surface 84d to be robustly maintained.

In the prior art design, a separate bearing disc 484 was placed between the pinion 478 and the spindle 40 and against the pinion 478, as shown in FIG. 9A. The bearing disc 484 will include an inner opening having a spline internal shape so that the bearing disc 484, like the pinion 478, fits over the splint red head 464. The bearing disc 484 also included a notch in its internal shape to hold the bending element 66 in place. Bending element 66 engages bearing disc 484, and then bearing disc 484 and bending element 66 will be positioned over the spline portion of tread head 464.

The approach described above does not include a separate bearing disc, and the bending element 66 may be simply inserted into the notch 86a and the cavity 84a and crimped by deforming the wall 84c.

Alternatively, another tread head 564 may be arranged to receive a separate bearing disc 584, as shown in FIG. 9B. In this approach, the unitary structure may include the body 74 and another type of flex element mount 586. The bearing disc 584 is sized and positioned to be located above the flexure element mounting 586.

When assembled, the bearing disc 584 rotates on the flexure element mount 586 due to the matching notches and protrusions that extend radially inward and outward on the bearing disc 584 and flexure element mount 586. Possibly held in place. The bending element mounting portion 586 includes an axially inner portion 586a and an axially outer portion 586b with respect to the body 74. The inner portion 586a has an outer shape that is configured to engage the inner shape of the bearing disc 584. The outer portion 586b is configured to engage a flexing element 66 when the flexing element 66 is flexed.

Bending element portion 586 includes protrusions 587a, b, c, d, e, and f disposed around the outer shape of bearing element portion 586. The protrusion 587a has an inner portion 587g and an outer portion 587h, the inner portion 587g has a trapezoidal shape, and the outer portion 587h has a pointed shape. The inner portion 587g engages the bearing disc 584 and the outer portion 587h engages the bending element 66.

The protrusion 587b has an elongated box shape with a radially outer flat surface. The protrusions 587c, d, e, and f have a box shape or a trapezoidal shape. It will be appreciated that other shapes for the protrusion 587 may be used.

Bending element mount 586 may also include radial recesses in the outer surface. The recess 588a is circumferentially disposed adjacent to the protrusion 587a, and the recess 588b is circumferentially disposed adjacent to the protrusion 586f. The recess 588c is arranged adjacent to the protrusion 586e in the circumferential direction.

The bearing disc 584 has a recess 584a corresponding to the protrusions 586a, b, c, d, e, and f of the flexing element mounting 586, and a recess 584b for receiving the flexing element 66. The recess is defined by a protrusion 585 extending radially inward from the internal shape of the bearing disc 584. The bearing disc 584 defines a flat surface 584c that conforms to the protrusion 586b. The bearing disc 584 may include a protrusion 584d disposed on one of the protrusions 585 and another protrusion 584e disposed on another one of the protrusions 585. The protrusion 584d corresponds to the recess 588c, and the protrusion 584e corresponds to the recess 588b.

The bending element 66 may be arranged in the bending element mounting portion 586, and the bearing disc 584 covers a part of the bending element 66 in the recess 584b, so that the bending element 66 is located between the bending element mounting portion 586 and the bearing disc 584. Hold. The bearing disc 584 will provide the bearing surface described above and the flexing element 66 will wrap around the flexing element mounting 586 in a manner similar to that described above.

The integral form of the tread head 64 or tread head 564 allows for a greater depth of space 78c between the pinion teeth 80 (for the multi-piece assembly of tread head 464, pinion 478 and bearing disc 484 of FIG. 9A). Yes, or can provide additional structural stability to the separate pinion 478. In the multi-piece design, the pinion 478 had to pass over the spline prongs of the tread head 464, thus limiting the depth of the pinion teeth. Therefore, the base of the space between the pinion teeth will always be radially outward of the outermost surface of the spline protrusion of the tread head 464, as the separate pinion 478 passes over the spline protrusion. The outermost surface of the tread head 464 protrusion beyond the bearing disk 484 also served as the surface around which the bending element 66 was wrapped.

In a one-piece design, the depth of the space 78c between the teeth 80 may extend into the body of the tread head 64 or tread head 564 and radially inward of the outermost surface of the flexure element mounting 86. This is not possible with conventional multi-piece designs.

The use of a one-piece design for a multi-piece design also offers manufacturing advantages. The tread head 64 or 564 may be die cast, sintered, or injection molded. The use of a one-piece design also reduces the overall tolerance width in the axial direction for multi-piece designs.

Accordingly, the integrated tread head pinion 64 or 564 couples with the spindle 40 as part of the spool assembly 34. The spool assembly 34 cooperates with other components of the retractor assembly 32, including components for pretensioning as well as components for normal operation of the retractor.

The spool assembly 34 includes a head pinion 64/564 located within the housing 54. The pinion 64/564 is attached to the belt spool 40. Rotation of the pinion 64/564 results in rotation of the attached belt spool 40 to wind the seat belt webbing 14 attached to the belt spool 40.

FIG. 10A provides an illustration of a side cross-section of pretensioner rod 53 and stopper 55, according to an exemplary embodiment. As shown in FIG. 10A, the pretensioner rod 53, in one form, has a generally circular cross section. In another approach, the pretensioner rod 53 allows the pretensioner rod 53 to be inserted into the pretensioner tube 52 (shown in FIG. 4) and, when inserted, conform to the serpentine shape of the pretensioner tube 52. Can have a non-circular cross section, such as a generally rectangular cross section, a generally triangular cross section, or other polygonal cross section. For purposes of discussion, pretensioner rod 53 is considered as having a generally circular cross section.

As illustrated and discussed above, the pretensioner rod 53 has a generally straight shape when disposed outside the pretensioner tube 52 and extends longitudinally from the proximal end portion 202 to the distal end portion 204. Extending to 200. Proximal end portion 202 is positioned toward gas generator 36 (shown in FIG. 10C) when pretensioner rod 53 is installed within pretensioner system 44. In the exemplary embodiment, pretensioner rod 53 has a cross-section that varies along its length to define a non-recessed portion 206 and a recessed portion 208 that defines a recess 210. In one example, and as illustrated in FIGS. 10A and 12, the recess 210 is configured as a groove, eg, a U-shaped groove with sidewalls.

With reference to FIG. 10A, in the exemplary embodiment, the recessed portion 208 extends from the proximal end portion 202 to the distal end portion 204, and includes the distal end portion 204, to a greater length of the pretensioner rod 53. Extends along the part. As illustrated, the proximal end portion 202 includes a non-recessed portion 206 and the recess 210 terminates in the most distal section of the non-recessed portion 206. As discussed in more detail below and as illustrated in FIG. 10A, the non-recessed portion 206 of the pretensioner rod 53 has a larger diameter, cross-sectional dimension, and/or perimeter than the recessed portion 208. Have. In the exemplary embodiment, non-recessed portion 206 has a length L1 of about 15-25 mm and a width W1 of about 4-7 mm, such as about 20 mm, and recessed portion 208 has a length of about 60-145 mm. It has a thickness L2 and a thickness W2 of about 2.5-8.0 mm.

In the exemplary embodiment, pretensioner rod 53 also includes positive features 216, such as protrusions or posts, extending proximally from proximal end portion 202. Stopper 55 has a negative feature 218 formed therein that receives positive feature 216 for coupling stopper 55 to proximal end portion 202 of pretensioner rod 53. In one embodiment, the negative feature 218 and the positive feature 216 include a stopper 55, such as an interference fit, on the positive feature 216 for fixedly coupling the stopper 55 to the pretensioner rod 53, for example. , Sized to be compression tightened. Other shapes for coupling and/or securing the stopper 55 to the positive feature 216 and/or the proximal end portion 202 may use, for example, adhesives, mechanical means, or the like. The positive feature 218 can be configured as a blind hole 220, as illustrated in FIG. 10A. Alternatively, and as illustrated in FIG. 10B, the negative feature 220 may be configured as a through hole 222 with the positive feature 216 extending partially or completely therein.

In the exemplary embodiment, pretensioner rod 53 is made from a polymeric material that has a reduced weight relative to the metal sphere drive elements of other rotopretensioners. The particular polymeric material can be selected to suit the needs of a particular user. The polymeric material is preferably sufficiently flexible to be able to bend and flex through the pretensioner tube 52, allowing for initial installation and actuation by the gas generator 36. The polymeric material has sufficient extrudability in response to actuation so that the pretensioner rod 53 transfers sufficient load to the tread head pinion 64 of the pretensioner system 44, thereby providing a pretensioning drive element. Those that work are preferred.

Further, in the exemplary embodiment, pretensioner rod 53 is made from a plastically deformable polymeric material. During and after actuation, the pretensioner rod 53 is plastically deformed in response to actuation and contact with other components of the pretensioner system 44 (eg, the tread head pinion 64). As discussed in more detail below, this plastic deformation results in the pretensioner rod 53 not being completely dependent on the pressure maintained within the system, such as within the treadhead pinion 64. It will result in being locked to prevent or limit payback.

In one approach, the pretensioner rod 53 is made from a nylon thermoplastic material. The pretensioner rod 53 can also be made from an aliphatic polyamide thermoplastic material. In another approach, the pretensioner rod 53 can be made from similar thermoplastic materials such as acetal or polypropylene materials.

Referring again to FIG. 4, the housing 54 further includes a guide portion 90. The guide portion 90 is located within the housing 54 similar to the tread head pinion 64. More specifically, the guide portion 90 is disposed on the opposite side of the outlet of the tube 52, and the tread head pinion 64 is disposed between the guide portion 90 and the tube 52. Therefore, the pretensioner rod 53 exiting the tube 52 comes into contact with the tread head pinion 64 before coming into contact with the guide portion 90.

The guide 90 has a generally arcuate landing surface 92 having a concave shape towards the outlet of the tube 52. In one approach, the arc of surface 92 has a constant radius. Further, the center point of the radius of the arc is aligned with the axis of rotation of the tread head pinion 64 such that the radial spacing between the surface 92 and the tread head pinion 64 matches along the length of the surface 92. .. In another approach, the center point of the radius of surface 92 is offset from the sprocket axis such that the radial spacing between surface 92 and the outer diameter of tread head pinion 64 varies at different points along surface 92. be able to.

The surface 92 includes a first end 96 and a second end 98. The first end 96 is adapted to engage the first end 96 prior to the second end 98 after the pretensioner rod 53 exits the tube 52 and passes through the tread head pinion 64. , On the side opposite to the outlet of the tube 52.

The housing 54 further defines an overflow cavity 100 located opposite the guide 90. The overflow cavity 100 is also located adjacent the bend in the tube 52 and the tread head pinion 64 is located between the guide 90 and the overflow cavity 100. Therefore, the middle portion 101 of the guide 90 is on the radially opposite side of the overflow cavity 100 across the tread head pinion 64.

Overflow cavity 100 is optionally sized and configured to allow pretensioner rod 53 to be received therein during operation of pretensioner system 44. For example, after the pretensioner rod 53 exits the tube 52, it contacts the guide 90 so that the pretensioner rod 53 is finally oriented towards the overflow cavity 100, and in an arcuate path corresponding to the guide 90. It will be directed. The pretensioner rod 53 can extend into the overflow cavity 100 and can be further guided along a bend in the tube 52 adjacent the overflow cavity 100. However, it will be appreciated that the pretensioner rod 53 may not necessarily advance sufficiently during operation to eventually reach the overflow cavity 100.

As explained above, the retractor assembly 32 includes a gas generator 36 that provides inflation gas in response to the firing signal. The inflation gas causes an increase in pressure within the tube 52 which causes the pretensioner rod 53 to pass from the gas generator 36 through the tube 52 and through the outlet and into the treadhead pinion 64 for pretensioning. And finally separated.

More specifically, as shown in FIG. 10C, the pretensioner tube 52 includes a piston or sealing member 102. The sealing member 102 can have a spherical shape with a spherical outer surface in one approach. In another approach, the sealing member 102 can have a generally cylindrical shape with a cylindrical outer surface. The sealing member 102 is slidably disposed within the tube 52 and is operable to drive the pretensioner rod 53 along the actuation direction or path A. As will be appreciated by those skilled in the art, the sealing member 102 can be press fit inside the tube 52 or otherwise fitted.

As shown in FIG. 10C, the sealing member 102 defines a proximal end 106 spaced from the gas generator 36 and a gas chamber 108 therebetween. The sealing member 102 defines a distal end 110 oriented toward the stopper 55 and the pretensioner rod 53.

Stopper 55 is preferably made of aluminum, but steel, other metals, or metal alloys, or reinforced plastic with a generally softer sealing member 102 such that it can provide the described sealing capabilities. Can also be made from another suitable material of sufficient strength. In the exemplary embodiment, stopper 55 has a perimeter that substantially conforms to the perimeter of non-recessed portion 206. The stopper 55 is adjacent to the distal end 110 of the sealing member 102 and abuts the non-recessed portion 206 of the pretensioner rod 53.

The sealing member 102 and the stopper 55 cooperate to transfer energy from the increased pressure in the gas chamber 108 to the pretensioner rod 53. The pretensioner rod 53 is sized slightly smaller than the width of the tube 52 as it advances through the tube 52 and flexes according to the bends in the tube 52. Therefore, without the sealing member 102, the gas from the gas generator 36 flows past the pretensioner rod 53 in the space defined between the pretensioner rod 53 and the tube 52.

The sealing member 102 generally defines an elastic structure and is known in the art, such as any suitable plastic or polymer (eg, polyester, rubber, thermoplastic, or other elastic or deformable material). It may consist of various materials. Further, the sealing member 102 may be die cast, forged, or molded from metal, plastic, or other suitable material. In one embodiment, the sealing member 102 is formed using a two cavity injection molding process. Generally, the elastic structure allows the shape of the sealing member 102 to change slightly in response to pressure, thereby improving the sealing it provides.

Referring to FIGS. 10 and 11, during operation, the gas generator 36 generates an inflation gas that pressurizes the gas chamber 108, which causes the sealing member 102 to force the pretensioner rod 53 along the actuation path A. It is possible to drive. As the pretensioner rod 53 is driven through the tube 52, it engages the tread head pinion 64. More specifically, the pretensioner rod 53 engages with the teeth 80 of the tread head pinion 64. As the pretensioner rod 53 is driven by the inflation gas in the direction of arrow A, the engagement of the pretensioner rod 53 with the tread head pinion 64 results in rotation of the belt spool 40 (shown in FIG. 3). Provide pretension.

Activation of the gas generator 36 allows the sealing member 102 to resist gas leaks. As mentioned above, the sealing member 102 is made of a relatively elastic material. Thus, the pressurized gas within the gas chamber 108 causes the proximal end 106 of the sealing member 102 to expand and prevent the gas from escaping through the sealing member 102.

In addition, the back pressure generated from the pretensioner rod 53 causes the sealing member 102 to expand outward in the circumferential direction due to the compression against the stopper 55 of the sealing member 102 and the pretensioner rod 53. The pretensioner rod 53 experiences resistance as it engages the tread head pinion 64 during operation, thereby creating a back pressure on the stopper 55 and the sealing member 102. The circumferential expansion of the sealing member 102 provides a clamped seal between the outer surface of the sealing member 102 and the inner wall of the pretensioner tube 52. Accordingly, the sealing member 102 of the present invention is operable to maintain a high sealing pressure as well as maintain a residual gas pressure within the tube 52.

During seatbelt pretensioning, a side effect known as payback, during the pretensioning event, seatbelt tension caused by the occupant may cause the spool to rotate in the opposite direction of the pretensioning rotation. This rotation is transmitted to the tread head pinion 64 and the drive element to drive the drive element in the tube 52 in the opposite direction. Payback can be countered by maintaining pressure in tube 52, which requires gas generator 36 to fire for a longer period of time and additional propellant.

However, in an exemplary embodiment, the pretensioner system 44 described herein provides the payback side effects described above as an alternative to, or in addition to, the maintained gas pressure. Including features configured to oppose. As explained above, the pretensioner rod 53 is preferably made from a plastically deformable material such as a polymer.

During operation of the pretensioner system 44, the pretensioner rod 53 exits the tube 52 and contacts the teeth 80 of the treadhead pinion 64, causing rotation of the treadhead pinion 64. As the pretensioner rod 53 passes through the tread head pinion 64 and effects its rotation, each of the additional teeth 80 contacts the sides of the pretensioner rod 53, causing the pretensioner rod 53 to contact the tooth 80 and the pretensioner rod 53. It will result in compression and plastic deformation in the interference region between. This compression will also result in the pretensioner rod 53 being compressed against the guide 90, creating a press fit configuration of the pretensioner rod 53 between the tread head pinion 64 and the guide 90.

Further, the pretensioner rod 53 and the guide 90 can be made of materials that will be welded together at the end of the pretension stroke. For example, the material of the pretensioner rod 53 and the guide 90 is such that the heat generated from the friction between the pretensioner rod 53 and the guide 90 causes the pretensioner rod 53 to move along the interface W where the guide 90 and the rod 53 contact each other. And the guide 90 may be selected to be welded together. Once the pretensioner rod 53 and the guide 90 are welded together, the pretensioner rod 53 becomes locked and prevents or substantially limits backflow into the tube 52. The plastic deformation of the pretensioner rod 53 caused by the teeth 80 will prevent or substantially limit the tread head pinion 64 from rotating in the opposite direction, thereby preventing or substantially limiting payback. ..

Welding results from the relatively high heat and pressure generated by the operating system. For the pretensioner rod 53 and the guide 90 to be welded, the material used for each is preferably within the same family. For example, when the guide 90 is nylon, the pretensioner rod 53 is preferably nylon. Similarly, when the guide 90 is acetal, the pretensioner rod 53 is preferably acetal. When the guide 90 is polypropylene, the pretensioner rod 53 is preferably polypropylene. It will be appreciated that other materials that will weld together under high heat and pressure can also be used. Further, it will be appreciated that several different types of materials can be welded together.

Another side effect that can occur during pretension is known as the low resistance state. This can occur when there is a relatively large portion of seat belt webbing that can be wound or wrapped by the spool in response to actuation of the pretensioner. For example, if there is extra slack in the seat belt, the slack does not affect the occupant until the slack has been wound up, resulting in low resistance winding or wrapping. In the low resistance state, the back pressure of the drive element is reduced. The reduced back pressure may result in a reduced ability of the sealing element to circumferentially expand to the inner wall surface of the tube in response to the back pressure. This can occur for any type of piston or seal configured to expand circumferentially in response to back pressure as part of the sealing process.

With reference to FIGS. 4, 8, 11 and 12, in order to address the side effects of the low resistance state of the pretensioner system 44, in an exemplary embodiment, the tube 52 is near the end of the tube 52. It includes a protrusion 120 extending into the tube 52 to form a constriction 130 proximate the location of the pretensioner rod 53, thereby reducing the cross-sectional area of the tube 52 at the distal location. That is, the diameter, width, or dimension(s) of the opening in the constricted portion 130 may be, for example, the diameter, width, or dimension of a portion adjacent to the portion of the tube 52, such as the portion of the tube 52 upstream from the constricted portion 130 ( Smaller than).

As will be discussed in more detail below, the recess 210 is in the actuation direction or path A such that the recessed portion 208 of the pretensioner rod 53 is not obstructed by the projection 120 during actuation and/or pretensioning. Along with the protrusion 120. Further, the constricted portion 130 is capable of advancing through the constricted portion 130 at least in the recessed portion 208 of the pretensioner rod 53, while preventing the stopper 55 and the sealing member 102 from advancing through the constricted portion 130. Is sized so that there is sufficient space such as When the stopper 55 and the sealing member 102 are prevented from advancing past the constricted portion 130, the constricted portion 130 provides additional back pressure. Accordingly, the sealing member 102 will expand circumferentially or radially in response to this back pressure, thereby providing improved sealing in the low resistance state. This improved seal will prevent or limit the possibility of gas escaping the tube in low resistance conditions.

The protrusion 120 that defines the constricted portion 130, while providing the functions described above, can be formed in various ways and have various shapes.

In the above approach, the recesses 210 and protrusions 120 of the pretensioner rod 53 aligned together may be located along the inboard portion of the tube 52, as illustrated in FIGS. 4 and 11, or alternatively. , And may be located along the outboard portion of tube 52, as illustrated in FIGS. Advantageously, in the exemplary embodiment, placement of protrusion 120 on the inboard portion of tube 52 facilitates pretensioner rod 53 sliding over the outboard portion of tube 52 during travel. .. The centrifugal force of the pretensioner rod 53 as it advances through the tube 52 tends to force the pretensioner rod 53 toward the outboard portion of the tube 52, and positioning the protrusion 120 on the inboard portion causes the constricted portion 130 to move. This reduces the possibility of adding resistance to the pretensioner rod 53. Alternatively, and advantageously, in the exemplary embodiment, placement of protrusion 120 on the outboard portion of tube 52 causes tread head pinion 64 to engage the entire or solid side of pretensioner rod 53 during operation. To facilitate mating (eg, the tread head pinion 64 engaging the side of the pretensioner rod 53 opposite the recess 210), either of the pretensioner rod 53 in the actuation direction or the direction opposite the path A. It facilitates locking of the pretensioner rod 53 with the tread head pinion 64 to prevent or reduce translation.

As explained above, the pretensioner rod 53 has a non-recessed portion 206 at its proximal end portion 202, the non-recessed portion 206 having a larger diameter or cross-sectional dimension (plurality) than the recessed portion 208. Yes). In one approach, the non-recessed portion 206 has a diameter or cross-sectional dimension(s) at the narrowed portion 130 that is greater than the width or cross-sectional dimension(s) of the tube 52. Therefore, in the non-recessed portion 206 arranged on the upstream side of the narrowed portion 130, the narrowed portion 130 prevents the non-recessed portion 206 from passing therethrough.

In another approach, the non-recessed portion 206 may be smaller than the width or cross-sectional dimension(s) of the tube 52 at the narrowed portion 130. If the non-recessed portion 206 is small enough to pass through the narrowed portion 130, it can pass over the narrowed portion 130.

Those skilled in the art will readily appreciate that the above description illustrates implementations of the principles of the invention. This description is intended to cover the scope of the invention or to the extent that the invention permits modifications, variations, and alterations without departing from the spirit of the invention as defined in the following claims. It is not intended to limit the application.

Claims (14)

A pretensioning device used in a seat belt retractor assembly,
A spindle configured to rotate about a longitudinal center axis and wind up a seat belt webbing;
A tread head pinion that is connected to the spindle and rotates the spindle by rotating according to an applied pre-tension load;
A deformable rod that translates along a predetermined path and that directly engages the tread head pinion, thereby rotating the tread head pinion,
The tread head pinion,
a) a first side facing away from the spindle and a second side facing the spindle;
b) a ring portion extending between the first side and the second side and having a plurality of radially projecting teeth for receiving the pretensioning load from the rod;
c) including first flanges on the first side and second flanges on the second side, disposed on opposite sides of the teeth, projecting radially outward beyond the teeth A pair of flanges, the flanges being longitudinally disposed adjacent to the plurality of teeth, the teeth being integral with the flange to form a cavity between the adjacent teeth and the flange. With the flange,
d) a bearing portion axially projecting from the second flange towards the spindle, the bearing portion defining a bearing surface against which the spindle abuts;
A bending element that can adjust the load applied to the occupant during pre-tension,
The tread head pinion is provided with a bending element mounting portion that axially projects toward the spindle so as to be separated from the bearing portion and that holds the bending element .
A pretensioning device, wherein the configurations a) to d) of the tread head pinion are integrally formed. The apparatus of claim 1, wherein the tread head pinion further comprises a shaft that axially projects away from the first side and the spindle. The apparatus according to claim 1 or 2 , wherein the bearing portion has a generally circular outer shape, and the outer diameter is smaller than the outer diameter of the second flange. The apparatus according to claim 3 , wherein the bending element mounting portion has a generally circular outer shape and an outer diameter is smaller than an outer diameter of the bearing portion. The device according to any one of claims 1 to 4, wherein the bending element is attached to the tread head pinion and the spindle. 6. The apparatus of any of claims 1-5 , wherein the flexure element mount defines a smooth outer peripheral surface over most of the circumference of the flexure element mount. The bending element mounting portion defines a notch on an outer periphery of the bending element mounting portion, said notches, extending towards the bearing unit from the axial outermost surface of the bent element mounting portion, according to claim 1 to 6 The apparatus according to claim 1. The bearing portion defines a crimping cavity axially disposed adjacent the notch of the bending element mounting portion, the crimping cavity extending from an axially outermost surface of the bearing portion into the bearing portion. The device of claim 7 , wherein the device is present. The bearing portion defines an access cavity located radially outward of the swaging cavity and adjacent to the swaging cavity, the access cavity extending from an outermost axial surface of the bearing portion to the bearing. 9. The device of claim 8 extending into the section. The bearing portion defines a crimping wall radially disposed between the access cavity and the crimping cavity, the crimping wall being radially deformable, and the bending element being the tread. The device according to claim 9 , wherein the device is swaged with respect to the head pinion. 11. A device according to any one of the preceding claims, wherein the entire bending element is arranged radially outward with respect to the bending element mounting. 12. A device according to any one of the preceding claims, wherein the ring portion has a radial thickness that extends radially inward beyond the outer circumference of the bending element mounting portion. The treadhead pinion defines a central internal cavity extending axially through the bearing portion and into the ring portion, the internal cavity having a spline surface for receiving a corresponding structure of a torsion bar. An apparatus according to any one of claims 1 to 12 . Wherein attached to one end of the tread head pinion, through the bearing portion, further comprising an extension to the torsion bar to the ring portion, the torsion bar is attached to said spindle at its opposite end, claims 1 to 12 The apparatus according to claim 1.